Oral care implement having multi-component handle

ABSTRACT

An oral care implement having a multi-component handle, and method of manufacturing the same. The invention can be a method of forming a handle for an oral care implement comprising: a) forming a core structure of a first hard plastic; b) forming an elongated handle body of a second hard plastic that at least partially surrounds the core structure so that opposing lateral surfaces of the core structure remain exposed; and c) forming a grip cover of a resilient material over at least a portion of the elongated handle body.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 14/023,077, filed Sep. 10, 2013, now allowed, which is acontinuation of U.S. patent application Ser. No. 12/641,698, filed Dec.18, 2009, which issued as U.S. Pat. No. 8,549,691 on Oct. 8, 2013, theentireties of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to oral care implements, andspecifically to oral care implements, such as toothbrushes, having ahandle constructed of multiple components and/or materials.

BACKGROUND OF THE INVENTION

Oral care implements, such as toothbrushes, are mass-produced articlesand must therefore allow cost-effective production. Toothbrushes made ofa single plastic material and toothbrushes made of two plasticcomponents, which are produced for example by a two component injectionmolding process, are known. In the latter case, known toothbrushesgenerally comprise two parts: a first part made of a hard plasticmaterial, for example polypropylene; and a second part made of aresilient plastic material, for example a thermoplastic elastomer.Typically, the first part, which is made of the hard plastic material,forms the structural portion of the handle and has a recess or channelformed therein. This recess is filled with the resilient plasticmaterial, thereby forming the second part which acts as a grippingsurface or cover.

The hard plastic and the resilient soft plastic are selected so thatthey bond with one another at the surface where the two plastic partstouch. In comparison with a toothbrush made of only one plasticmaterial, this provides greater scope for design. Since, however, thetwo plastic materials have to bond with one another during theinjection-molding operation, there are restrictions in the selection ofthe plastic materials and consequently in the design of the toothbrush.

One solution to the limitation that two plastic materials must bond withone another during the injection molding operation has been introducedby which a handle can be formed by two plastics that do not chemicallybond within one another during the injection molding operation butrather utilize a mechanical connection, such as by inter-fittingportions of the two plastic components or by shrinking one plasticcomponent about the other. With respect to creating a two componenttoothbrush having a grip cover over a hard plastic body, this knownmethod is limited in its design capability to a tubular sleeve thatreceives a cylindrical core structure within its cavity so as tocircumferentially surround the entire circumference of the cylindricalcore structure. This arrangement is limiting in both possible designsfor the handle and the fact that the resulting handle must either bebulky or sacrifice strength.

Another oral care implement having a multi-component handle that isknown in the art includes a gripping region having a thermoplasticelastomer (“TPE”) grip surface with a plurality of spaced slot openingsexposing portions of a hard plastic base. This handle also includes aninclined portion and a soft TPE grip body extending through the hardplastic base of the handle to form opposite finger grips on the inclinedportion of the handle. This soft grip body provides shifting of a masscentroid during use. In this construction, the handle of the oral careimplement comprises three components, a hard plastic handle body, a gripcover/surface formed of a first TPE, and a grip body formed of a secondTPE which is softer than the first TPE.

A need exists for an oral care implement, and method of manufacturingthe same, that has a handle having greater design flexibility, is morecost-effective to mass produce, and/or affords comfort and control tothe user during use.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed to an oral care implementhaving a multi-component handle constructed of at least four componentsconstructed of different materials. In another aspect, the invention isdirected to an oral care implement having a multi-component handlehaving a core structure, an elongated handle structure at leastpartially surrounding the core structure, and a grip cover strategicallylocated on the elongated handle body to conceal through holes in theelongated body resulting from supporting the core structure during theinjection molding process.

In one embodiment, the invention may be an oral care implementcomprising: a handle having a proximal end and a distal end; a headconnected to the distal end of the handle; the handle comprising a firstcomponent constructed of a first material, a second componentconstructed of a second material, a third component constructed of athird material and a fourth component constructed of a fourth material.

In another embodiment, the invention may be an oral care implementcomprising: a head; a handle having a distal end and a proximal end, thehead connected to the distal end of the handle; the handle comprising acore structure constructed of a first rigid material and an elongatedhandle body constructed of a second rigid material, the core structuredisposed within a through slot of the elongated handle body so that thecore structure is exposed on opposite lateral surfaces of the handle;and a grip cover constructed of a resilient material, the grip covercovering a front surface, a rear surface and a proximal end surface ofthe elongated handle body.

In a further embodiment, the invention may be an oral care implementcomprising: a head; a handle having a distal end and a proximal end, thehead connected to the distal end of the handle; the handle comprising acore structure constructed of a first rigid material and an elongatedhandle body constructed of a second rigid material that does not form achemical bond with the first material during an injection moldingprocess; the core structure disposed within a through slot of theelongated handle body so that the core structure is exposed on oppositesurfaces of the handle; at least one through hole on a first surface ofthe elongated handle body through which the core structure is exposedand at least one through hole on a second surface of the elongatedhandle body through which the core structure is exposed, the secondsurface opposite the first surface; the core structure comprising afirst protuberance that extends into the through hole on the firstsurface of the elongated handle body and a second protuberance thatextends into the through hole on the second surface of the elongatedhandle body; and a grip cover constructed of a resilient materialcovering the through hole on the first surface of the elongated handlebody and the through hole on the second surface of the elongated handlebody, the resilient material forming a chemical bond with the secondmaterial during an injection molding process.

In a yet further embodiment, the invention may be a method of forming ahandle for an oral care implement comprising: a) injecting a liquefiedfirst plastic into a first mold cavity to form a core structure of thefirst plastic; b) supporting the core structure within a second moldcavity with a gripping member that contacts the core structure at two ormore points of contact on opposite surfaces of the core structure; c)injecting a liquefied second plastic into the second mold cavity to forman elongated handle body that at least partially surrounds the corestructure, thereby forming a handle assembly, the elongated handle bodysurrounding the gripping member resulting in a through hole in theelongated handle body for each point of contact, the points of contactexposed via the through holes; d) supporting the handle assembly in athird mold cavity; and e) injecting a liquefied resilient material intothe third mold cavity to form a grip cover over the elongated handlebody, the grip cover overlying the through holes.

In still a further embodiment, the invention may be an oral careimplement comprising: a head; a handle having a distal end and aproximal end, the head connected to the distal end of the handle; thehandle comprising a core structure constructed of a transparent rigidmaterial and an elongated handle body constructed of an opaque rigidmaterial; the core structure disposed within a through slot of theelongated handle body so that the core structure is exposed on oppositesurfaces of the handle so as to form a window through the handle; and aplurality of facets formed into an interior of the core structure thatare visible through the window and reflect visible light.

In an even further embodiment, the invention can be a method of forminga handle for an oral care implement comprising: a) forming a corestructure of a first hard plastic; b) forming an elongated handle bodyof a second hard plastic that at least partially surrounds the corestructure so that opposing lateral surfaces of the core structure remainexposed; and c) forming a grip cover of a resilient material over atleast a portion of the elongated handle body.

In another embodiment, the invention can be an oral care implementcomprising: a handle having a proximal end and a distal end; a headconnected to the distal end of the handle; the handle comprising a corestructure comprising a first rigid material, an elongated handle bodycomprising a second rigid material, a grip cover comprising a resilientmaterial; wherein the elongated handle body comprises the head; andwherein the core structure is disposed in a through slot that extendsfrom opposite surfaces of the elongated handle body, and whereinsurfaces of the core structure remain exposed via the through slot.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is capable of use in a broad array of oral careimplements and hygiene products. The drawings illustrate one use of theinvention and are not to be construed as the only embodiment of theinvention.

FIG. 1 is a perspective view of an toothbrush according to oneembodiment of the present invention.

FIG. 2 is a front view of the toothbrush of FIG. 1 according to oneembodiment of the present invention.

FIG. 3 is a rear view of the toothbrush of FIG. 1 according to oneembodiment of the present invention.

FIG. 4 is a left side lateral view of the toothbrush of FIG. 1 accordingto one embodiment of the present invention, the right side lateral viewof which is a mirror image.

FIG. 5 is a longitudinal cross-sectional view of the toothbrush of FIG.1 taken along view V-V of FIG. 2 according to one embodiment of thepresent invention.

FIG. 6 is a lateral cross-sectional view of the toothbrush of FIG. 1taken along view VI-VI of FIG. 3 according to one embodiment of thepresent invention.

FIG. 7 is a perspective view of the toothbrush of FIG. 1 showing thefour components of the handle in an exploded state according to oneembodiment of the present invention.

FIG. 8 is a perspective view of a core structure of the handle of thetoothbrush of FIG. 1 according to one embodiment of the presentinvention.

FIG. 9 is a perspective view of a handle assembly consisting of the corestructure of FIG. 8 with the elongated handle body overmolded theretoaccording to one embodiment of the present invention.

FIG. 10 is a perspective view of the handle consisting of the handleassembly of FIG. 9 with the grip cover overmolded to the elongatedhandle body according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, the invention is discussed in terms of amanual toothbrush, and method of manufacturing the same, having theinventive multi-component handle. However, in other forms, the inventioncould be in the form of other oral care implements including asoft-tissue cleansing implement, an inter-proximal pick, a flossingtool, a plaque scraper, a powered toothbrush, or other ansate implementdesigned for oral care. It is also to be understood that otherembodiments may be utilized, and that structural and functionalmodifications may be made without departing from the scope of thepresent invention.

Referring first to FIGS. 1-4 concurrently, a toothbrush 100 isillustrated according to one embodiment of the present invention. Thetoothbrush 100 generally comprises a handle 110 and a head 120. Thehandle 110 provides the user with a mechanism by which he/she canreadily grip and manipulate the toothbrush 100. The handle 110 includesergonomic features which provide a high degree of control for the userwhile maintaining comfort. The head 120 is connected to a distal end 102of the handle 110 and includes a set of teeth cleaning elements 130,which are generically illustrated.

Generally, the toothbrush 100 extends from a proximal end 101 (which isalso the proximal end of the handle 110) to a distal end 102 along alongitudinal axis A-A (illustrated in FIG. 2). Conceptually, thelongitudinal axis A-A is a reference line that is generally coextensivewith the three-dimensional center line of the handle 110 and the head120. Because the handle 110 is a non-linear structure (as can be seen inFIG. 4 as viewed laterally) in the illustrated embodiment, thelongitudinal axis A-A for toothbrush 100 is also non-linear in theillustrated embodiment. However, the invention is not so limited, and incertain embodiments, the toothbrush may have a simple linear arrangementand thus a substantially linear longitudinal axis A-A.

The head 120 is operably connected to the handle 110. As discussed ingreater detail below, the head 110 and the handle 120 of the toothbrush100 are preferably formed as an integral structure using an injectionmolding process. More specifically, in the exemplified embodiment, thehead 120 is integrally formed with the elongated handle body 150(discussed in greater detail below). However, in other embodiments, thehandle 110 and the head 120 may be formed as separate components whichare operably connected at a later stage of the manufacturing process byany suitable technique known in the art, including without limitationthermal welding, sonic welding, a tight-fit assembly, a coupling sleeve,adhesion, or fasteners. Whether the head 120 and the handle 110 areconstructed as an integral piece or a multi-piece assembly (includingconnection techniques) is not limiting of the present invention in allembodiments. Furthermore, other manufacturing techniques may be used inplace of and/or in addition to injection molding to create the handle110 and/or the head 120 (or components thereof), such as milling and/ormachining.

It should be noted that relative terms such as distal, middle, proximal,upper, lower, top, bottom, lateral, front, rear, left, right etc. aremerely used to delineate relative positions of the components of thetoothbrush 100 with respect to one another and are not intended to be inany further way limiting of the present invention.

The head 120 generally comprises a front surface 121 and a rear surface122. The front surface 121 and the rear surface 122 of the head 120 cantake on a wide variety of shapes and contours, none of which arelimiting of the present invention. For example, the front and rearsurfaces 121, 122 can be planar, contoured or combinations thereof. Thefront surface 121 and rear surface 122 are bound by a peripheral orlateral surface 123.

The set of teeth cleaning elements 130, which are genericallyillustrated as a block, are provided on and extend outward from thefront surface 121 of the head 120 for cleaning contact with an oralsurface, preferably teeth. While the set of cleaning elements 130 isparticularly suited for brushing teeth, the set of cleaning elements 130can also be used to clean oral soft tissue, such as a tongue, gums, orcheeks instead of or in addition to teeth. As used herein, the term“cleaning element” is used in a generic sense to refer to any structurethat can be used to clean or massage an oral surface through relativesurface contact.

Common examples of “cleaning elements” include, without limitation,filament bristles, fiber bristles, nylon bristles, spiral bristles,rubber bristles, elastomeric protrusions, flexible polymer protrusions,co-extruded filaments, flag bristles, crimped bristles, anti-bacterialbristles and combinations thereof and/or structures containing suchmaterials or combinations.

The set of cleaning elements 130 can be connected to the head 120 in anymanner known in the art. For example, anchor free tufting (AFT) could beused to mount the cleaning elements. In AFT, a plate or membrane issecured to the brush head such as by ultrasonic welding. The bristles(or other elastomeric elements) extend through the plate or membrane.The free ends of the bristles on one side of the plate or membraneperform the cleaning function. The ends of the bristles on the otherside of the plate or membrane are melted together by heat to be anchoredin place. Any suitable form of cleaning elements may be used in thebroad practice of this invention. Alternatively, the bristles could bemounted to tuft blocks or sections by extending through suitableopenings in the tuft blocks so that the base of the bristles is mountedwithin or below the tuft block. Staple technology may also be used.

Furthermore, if desired, the rear surface 122 may also compriseadditional structures for oral cleaning, such as a soft tissue cleanser.Such soft tissue cleansers are typically constructed of a TPE andinclude one or more projections, such as nubs and/or ridges, forengaging and massaging soft oral tissue, such as the tongue.

The handle 110 of the toothbrush 100 generally comprises a front surface111 and a rear surface 112 which is opposite the front surface 111. Thehandle 110 also comprises a right lateral surface 113 and a left lateralsurface 114 opposite the right lateral surface 113. As best visible inFIG. 6, the front surface 111, the rear surface 112, the right lateralsurface 113 and the left lateral surface 114 collectively form the outersurface of the handle 110, which has a generally elliptical lateralcross-sectional shape along its longitudinal length.

As will be described in greater detail below, the overall front surface111 of the handle 110 is formed by the collective of the outer surface163 of the front leg 161 of the grip cover 160, the front surface 171 ofthe grip body 170, and a portion of the front surface 151 of theelongated handle body 150. Similarly, the overall rear surface 112 ofthe handle 110 is formed by the collective of the outer surface 164 ofthe rear leg 162 of the grip cover 160, the rear surface 172 of the gripbody 170, and a portion of the rear surface 152 of the elongated handlebody 150. The overall right lateral surface 113 of the handle 110 isformed by the collective of the right lateral surface 153 of theelongated handle body 150 and the right lateral surface 141 of the corestructure 140. Similarly, the overall left lateral surface 114 of thehandle 110 is formed by the collective of the left lateral surface 154of the elongated handle body 150 and the left lateral surface 142 of thecore structure 140.

As best shown in FIGS. 2-4, the handle 110 can be conceptuallydelineated in longitudinal sections comprising a proximal section 115, amiddle section 116 and a neck section 117. The proximal section 115 isthe portion or segment of the handle 110 that generally fits comfortablywithin the palm of the user. The middle section 116 forms the portion orsegment of the handle 110 that generally fits comfortably between theuser's thumb and index finger. The neck portion forms the portion orsegment of the handle 110 that connects to the head 120.

The proximal section 115 longitudinally extends from the proximal end101 of the toothbrush 100 to the middle section 116. The middle section116 longitudinally extends from the proximal section 115 to the necksection 117. The neck section 117 extends from the middle section 116 tothe head 120. While the head 120 is illustrated as being widenedrelative to the neck section 117 of the handle 110, the head 120 couldin some constructions simply be a continuous extension or narrowing ofthe neck section 117 of the handle 110. The proximal section 115comprises a transverse cross-sectional area that gradually increasesfrom the proximal end 101 of the toothbrush 100 to a middle point MP1 ofthe proximal section 115. The transverse cross-sectional area of theproximal section 115 then gradually decreases from the middle point MP1to the transition point TP1 between the proximal section 115 and themiddle section 116. The middle section 116 has a transversecross-sectional area that gradually increases from the transition pointTP1 to the middle point MP2 of the middle section 116 and then graduallydecreases from the middle point MP2 to the transition point TP2 betweenthe middle section 116 and the neck section 117. The transversecross-sectional area of the neck section 117 gradually decreases fromthe transition point TP2 to the middle point MP3 of the neck section andthen increases from the middle point MP3 to the head 120. The handle 110of the toothbrush 100 preferably has a maximum transversecross-sectional area at middle point MP1 of the proximal section 115.The increasing and decreasing transverse cross-sectional area discussedabove results in a handle 110 having an undulating structure which ismore reliably and comfortably held within the user's hand. Further, thiswide construction of the proximal and middle sections 115, 116 requiresless fine motor control by the user and is, hence, easier to hold andmanipulate.

Referring solely to FIG. 4, the middle section 116 is angled withrespect to the proximal section 115 and the neck section 117. Thought ofanother way, the middle section 116 is inclined relative to the proximalsection and the neck section to define an inclined portion or segment ofthe handle 110 that is positioned for comfortable gripping and tofacilitate a desired offset positioning of the head relative to theproximal section 115. The angle of the incline is preferably 23 degrees,but may range between 5 to 40 degrees. The inclined nature of the middlesection 116 relative to the proximal and neck sections 115, 117 allowsfor improved control of the handle 110 during brushing in which the head120 can be more desirably positioned within the mouth to engage thetooth cleaning elements 130 against the teeth.

The core structure 140 is located within the proximal section 115 of thehandle 110. The grip body 170 is located within the middle section 116of the handle 110. The grip cover 160 covers both the proximal section115 and the middle section 116 of the handle 110.

Referring now to FIG. 7, the handle 110 is illustrated in an explodedstate so that its four components are visible. The four components ofthe handle 110 include a core structure 140, an elongated handle body150, a U-shaped grip cover 160 and a grip body 170. These componentscooperatively form an ergonomic and cost effective handle 110 by whichthe user holds and manipulates the toothbrush. The structure of each ofthese components will now be described in detail.

The core structure 140 is an elongated structure extending from aproximal end 146 to a distal end 147. The core structure has a generallyovoid shaped solid body 145. The solid body 145 comprises a rightlateral surface 141, a left lateral surface 142, a front surface 143 anda rear surface 144. The rear surface 144 is opposite the front surface143 while the right lateral surface 141 is opposite the left lateralsurface 142. All of the surfaces 141-144 are preferably convex surfaces,thereby giving the core structure 140 an elliptical transversecross-sectional area that tapers toward both the proximal and distalends 146, 147. Of course, the core structure can take on other shapesand sizes. Collectively, the surfaces 141-144 form the outer surface ofthe core structure 140.

A first protuberant structure 148 is located at the distal end 147 ofthe solid body 145. A second protuberant structure 149 is located at theproximal end 146 of the solid body 145. The first protuberant structure148 comprises a first upper protuberance 240 protruding outward from thefront surface 143 of the solid body 145 and a first lower protuberance241 protruding outward from the rear surface 144 of the solid body 145.The second protuberance structure 149 comprises a second upperprotuberance 242 protruding outward from the front surface 143 of thesolid body 145 and a second lower protuberance 243 protruding outwardfrom the rear surface 144 of the solid body 145. While two pairs ofprotuberances 240-241 and 242-243 are exemplified, the core structure140 may of course have more or less protuberances as desired. Moreover,such protuberances may be located in different positions on the body 145either longitudinally or laterally, or be omitted all together.

The first upper protuberance 240 comprises a contact surface 244. Thesecond upper protuberance 243 comprises a contact surface 246. The firstlower protuberance 241 comprises a contact surface 245. The second lowerprotuberance 243 comprises a contact surface 247. While it is desirablethat the contact surfaces 244-247 be located on the protuberantstructures 148, 149, the invention is not so limited and the contactsurfaces 244-247 may be located directly on the body 145 in alternativeembodiments. As will be described in greater detail below, the contactsurfaces 244-247 provide points of contact that are used to support thecore structure 140 during subsequent steps of the manufacturing process.Furthermore, and as will also be discussed in greater detail below, theprotuberant structures 148, 149 mechanically engage the elongated handlebody 150 to provide structural integrity to the handle 110 byprohibiting unwanted relative movement between the core structure 140and the elongated handle body 150.

The rear surface 144 of the core structure comprises a plurality ofarcuate grooves 248 that form depressions in the rear surface 144 of thecore structure 140. The grooves 248 are preferably arcuate in shape andextend laterally across the substantial entirety of the width of therear surface 144 in a spaced-apart manner. The arcuate grooves 248 arearranged in pairs wherein the two arcuate grooves 248 in each pair areoriented so that their concave sides oppose one another, therebycollectively forming a segmented circular groove.

Of course, other types of grooves and or ridges can be provided on theouter surface of the core structure 140 if desired. For example, a pairof spaced apart longitudinally extending linear grooves 249 could beprovided on both the front and rear surfaces 143, 144 of the corestructure 140 between which the arcuate grooves 248 are located.

The core structure 140 is preferably a unitary single componentconstructed of a rigid material, such as for example a hard plastic.Suitable hard plastics include polyethylene, polypropylene (PP),polyamide, polyester, cellulosics, SAN, acrylic, ABS or any other of thecommonly known thermoplastics used in toothbrush manufacture.Preferably, the core structure 140 is constructed of a transparent rigidmaterial. Suitable transparent rigid materials include withoutlimitation clarified PP and clear polyesters, such as polyethyleneterephthalate or a copolyester, such as poly-cyclohexylene dimethyleneterephthalate, acid modified, polyester (PCTA) or styrene acrylonitrile(SAN), acrylonitrile butadiene styrene (ABS), polymethyl methacrylate(PMMA) or a cellulosic plastic, such as cellulose acetate propionate(CAP). Most preferably, the core structure is constructed of asubstantially transparent SAN due to the benefits relating to cost,clarity and hardness characteristics.

When the core structure 140 is constructed of a transparent hardplastic, such as SAN, the grooves 248 formed into the rear surface 144of the body 145 are visible through both the right and left lateralsurfaces 141, 142 of the core structure 140 (which remain exposed whenthe toothbrush 100 is in an assembled state). As a result, thetopography of the grooves 248 (formed by the floors and upstandingsidewalls of the grooves 248) act as facets that create the visibleappearance of a shimmer or sparkle by deflecting and/or reflectingvisible light, similar to the effect created by the facets of a diamond.Of course, in some embodiments of the invention, this shimmer or sparkleeffect can be achieved by forming facets within the solid body 145itself or in one or both of the front and rear surfaces 143, 144.

The elongated handle body 150 is preferably a unitary structure thatintegrally comprises the head 120 and provides the general structure andshape for the handle 110 of the toothbrush 100. The elongated handlebody 150 comprises a front surface 151, a rear surface 152, a rightlateral surface 153 and a left lateral surface 154. The rear surface 152is opposite the front surface 151 while the right lateral surface 153 isopposite the left lateral surface 154. Collectively, the surfaces151-154 form the outer surface of the elongated handle body 150.

The elongated handle body 150 comprises an aperture 155 extendingthrough the elongated handle body 150 from the top surface 151 to thebottom surface 152. The aperture 155 forms a laterally orientedpassageway through the elongated handle body 150 and is provided toreceive the grip body 170 (discussed in greater detail below). Theaperture 155 preferably occupies more than one-half of the transversecross-sectional area at point MP2. Nevertheless, other constructions arepossible. The aperture 155 is located in the middle portion 116 of thehandle 110.

The aperture 155 is defined by a sidewall 156 (FIG. 5) that tapers withincreasing depth from both the front and rear surfaces 151, 152 of theelongated handle body 150, thereby coming to an annular apex/edge 157(FIG. 5) that is located within the aperture 155 and is the narrowestpart of the aperture 155. This dual-tapered sidewall geometry retainsand allows dynamic positioning of the resilient grip body 170 during useof the toothbrush 100 and provides a weight shifting feature whichimproves control of the handle 110 during use.

The sidewall 156 of the aperture 155 extends beyond the front surface151 and the rear surface 152 of the elongated handle body 150, therebyforming an annular ridge (or rim) 158 that protrudes from the frontsurface 151 of the elongated handle body 150 and an annular ridge (orrim) 159 that protrudes from the rear surface 152 of the elongatedhandle body 150. The annular ridges 158, 159 circumferentially surroundthe aperture 155 on both the front and rear surfaces 151, 152 of theelongated handle body 150.

The elongated handle body 150 further comprises a through slot 250 whichis formed by an inner surface 251. The through slot 250 extends from theright lateral surface 153 to the left lateral surface 154 of theelongated handle body 150, thereby forming a laterally extendingpassageway through the elongated body 150. The through slot 250 islocated in the proximal section 115 of the handle 110. Preferably, thethrough slot 250 is arranged at an approximately 90 degree offset fromthe aperture 155 (as measured circumferentially about the longitudinalaxis A-A of the handle 110). The through slot 250 has a longitudinalcross-sectional area that occupies a majority of the longitudinalcross-sectional area of the proximal section 115 of the handle 110.Thought of another way, the through slot 250 occupies a majority of thevolume of the proximal section 115 of the handle 110, preferably in arange of 55% to 95% and more preferably in a range of 75% to 90% of thevolume of the proximal section 115 of the handle 110.

A plurality of internal projections, which are illustrated in the formof ridges 252, are provided that protrude from the inner surface 251 ofthe elongated handle body 150 and into the cavity of the through slot250. Of course, the internal projections can take on other shapes, suchas nubs, walls, mounds, etc.

The internal ridges 252 are preferably arcuate in shape and extendlaterally across the substantial entirety of the width of the innersurface 251 in a spaced-apart manner. The arcuate internal ridges 252are arranged in pairs wherein the two arcuate internal ridges 252 whichmake up each pair are oriented so that their concave sides oppose oneanother, thereby collectively forming a segmented circular internalridge. The internal ridges 252 are sized and shaped to correspond to thegrooves 248 of the core structure 140. As will be discussed in greaterdetail below, when the toothbrush 100 is assembled and the corestructure 140 is disposed within the through slot 250 of the elongatedhandle body 150, the ridges 252 of the elongated handle body 150 extendinto and fill the grooves 248 of the core structure 140. The cooperationof the ridges 252 and the grooves 248 helps mechanically secure the corestructure 140 within the through slot 250 so that the core structure 140does not become dislodged from the elongated handle body 150 duringrepeated use of the toothbrush 100.

A pair of longitudinally extending linear ridges 253 also protrude fromthe inner surface 251 into the cavity of the through slot 250. Thearcuate ridges 252 are located between the linear ridges 253. Theselinear ridges 253 extend into and fill the linear grooves 249 of thecore structure 140 when the core structure 140 is disposed within thethrough slot 250.

A longitudinally extending channel 254 (which can also be referred to asa groove or depression) is provided in the outer surface of theelongated handle body 150. The channel 254 is a U-shaped channel thatstarts on the front surface 151 of the elongated handle body 150, wrapsaround a proximal end 255 of the elongated handle body 150, andcontinues onto the rear surface 152 of the elongated handle body 150.More specifically, the channel 254 extends longitudinally from thetransition point TP2 on the front surface 151 to the proximal end 255,wraps around the proximal end 255, and extends longitudinally from theproximal end 255 back to the transition point TP2 on the rear surface152. The channel 254 thereby extends along both the proximal section 115and middle section 116 of the handle 110. The channel 254 surrounds theaperture 155 on both the front and rear surfaces 151, 152 (specificallythe annular ridges 158, 159). As will be described in greater detailbelow, the channel 254 receives and is filled with the grip cover 160.

A plurality of through holes 256 are provided in the elongated handlebody 150 that form passageways into the through slot 250 from the frontand rear surfaces 151, 152. In the illustrated embodiment, two throughholes 256 are provided on each of the front and rear surfaces 151, 152of the elongated handle body 150 within the channel 254. The throughholes 256 on the front surface 151 are generally aligned with thethrough holes 256 on the rear surface 152. A first pair of the throughholes 256 are located adjacent the proximal end 255 of the elongatedhandle body 150 while a second pair of the through holes 256 are locatedadjacent the transition point TP1. Of course, more or less of thethrough holes 256 can be provided as needed and their location can bevaried. As described in greater detail below, the through holes 256 arethe result of the tooling used to support the core structure 140 duringthe injection overmolding of the elongated handle body 150 about thecore structure 140. However, the through holes 256 also receive theprotuberances 240-243 of the core structure to provide a mechanicalconnection between the core structure 140 and the elongated handle body150 when the core structure 140 is disposed within the elongated handlebody 150.

At least one outer projection 257 (best visible in FIGS. 3 and 5) isprovided on the rear surface 152 of the elongated handle body 150.Preferably, a plurality of spaced apart outer projections 257 areprovided that protrude from the rear surface 152. While the outerprojections 257 could have virtually any shape, they are preferably inthe form of spaced-apart arcuate ridges (or ribs) that laterally extendthe width of the rear surface 152. In the preferred embodiment, theouter arcuate ridges 257 correspond to the arcuate internal ridges 252in shape and positioning on the elongated handle body 150. The arcuateouter ridges 257 are arranged in pairs wherein the two arcuate outerridges 257 which make up each pair are oriented so that their concavesides oppose one another, thereby collectively forming a segmentedcircular internal ridge.

The arcuate outer ridges 257 preferably span laterally between thelateral surfaces 113, 114 of the handle 110, although they may havedifferent transverse lengths. The transverse length of each arcuateouter ridge 257 generally matches the width at the longitudinal locationalong the handle 110. However, the arcuate outer ridges 257 arepreferably slightly short of the actual width of handle 110 at any onelocation so as to be covered on the sides by grip cover 160. Sincearcuate outer ridges 257 span the width of the handle 110 in theproximal and middle sections 115, 116, they each have varying lengthsdue to the variations in the width of these sections 115, 116.

As a result of the spaced-apart arrangement of the arcuate outer ridges257, a transverse channel or groove is defined between each of theadjacent arcuate outer ridges 257. These transverse channels areconfigured to receive and retain the material of the grip cover 160,such as a thermoplastic elastomer (TPE) or other similar materials usedin oral care products.

The elongated handle body 150 is preferably a unitary single componentconstructed of a rigid material, such as for example a hard plastic.Suitable hard plastics include polyethylene, polypropylene (PP),polyamide, polyester, cellulosics, SAN, acrylic, ABS or any other of thecommonly known thermoplastics used in toothbrush manufacture.Preferably, the elongated handle body 150 is constructed of a hardplastic material that is a different type of plastic than the hardplastic material of which the core structure 140 is constructed. Mostpreferably, the elongated handle body is constructed of an opaque PP.

The grip cover 160 is a generally U-shaped (or tong-shaped) cover orlayer of resilient material. The grip cover 160 is fixed to theelongated base handle 150 to provide a gripping surface to improveperformance during use. The grip cover 160 is positioned within thechannel 254 of the elongated handle base 150 when the toothbrush 100 isin an assembled state.

The grip cover 160 conceptually comprises three sections, a front leg161, a rear leg 162 and a curved segment 165 that connects the front andrear legs 161, 162 in an opposing manner. The overall shape and size ofthe front and rear legs 161, 162 are mirror images of one another and,thus, are equal in length, width and overall shape and size. A firstopening 167 is provided in the front leg 161 while a second opening 168is provided in the rear leg 162. The first and second openings 167, 168receive the annular ridges/rims 158, 159 of the elongated handle body150 when the grip cover 160 is fixed to the elongated handle body 150.

The rear leg 162 comprises a plurality of spaced-apart openings 166,preferably in the form of arcuate slots that extend transversely acrossthe rear leg 162. The openings 166 are sized, shaped and positioned tobe aligned with the outer arcuate ridges 257 of the elongate handle body150. When the grip cover 160 is fixed to the elongate handle body 150,the outer arcuate ridges 257 extend into the openings 166 and are thusexposed via the openings 166. To form openings 166, suitable injectionmolding equipment mates with the top surfaces of the outer arcuateridges 257 to prevent overmolding of the outer arcuate ridges 257 andany undesired deflection of the elongated handle base 150 during themolding process. This enables the top surfaces of the outer arcuateridges 257 to be exposed after the molding process that adds the gripcover 160 to the base 150.

As can be seen best in FIG. 5, the top surfaces of the outer arcuateridges 257 are preferably recessed in the openings 166 relative to theouter surface 164 of the rear leg 162 of the grip cover 160. In otherwords, the grip cover 160 is created to have a sufficient thickness soas to control the depth of the openings 166. By ensuring that the topsurfaces of the outer arcuate ridges 257 are depressed relative to theouter surface 164 of the rear leg 162 of the grip cover 160, theopenings 166 prevent slippage of the handle 110 by enabling portions ofthe user's fingers to slightly protrude into the depth of the openings166. Additionally, openings 166 channel water away from the fingers tipsduring wet operational conditions. Air is also able to enter theopenings during brushing to provide some evaporative effect.

The grip cover 160 is preferably constructed of a resilient material,such as a thermoplastic elastomer (TPE). To provide comfort as well ascontrol benefits, the elastomeric material of the grip cover 160preferably has a hardness durometer measurement in the range of A13 toA50 Shore hardness, although materials outside this range may be used. Amore preferred range of the hardness durometer rating is A25 to A40Shore hardness. Furthermore, while an injection molded construction ofthe grip cover 160 is preferred, the grip cover 160 may, in someembodiments, be formed as a thin layer and attached to elongated handlebase 150 with an appropriate adhesive, sonic welding, thermal welding orother technique.

The grip body 170 is a generally bulbous shaped body that bulges out ofthe aperture 155 of the elongated handle body 150. The grip body 170fills the aperture 155 of the elongated handle body 150 and, thus, takeson the shape of the aperture 155. The grip body has a convex frontsurface 171 and a convex rear surface 172, which resemble an oval orelliptical shape. The bulbous shape of the grip body 170 enables theuser to reliably roll and control the handle 110 between the thumb andindex fingers during use. The grip body 170 may also be non-bulging orhave any number of shapes, such as circular, a true oval shape and thelike.

In one preferred construction, the grip body 170 has a multiplicity offinger grip protrusions 173 projecting from the front and rear surfaces171, 172. The finger grip protrusions 173 provide a tactile feature toincrease the friction on the user's finger surfaces and thus enhance theuser's ability to grip the handle 110, particularly under wetconditions. The finger grip protrusions 173 are preferably provided in adesired conical or frusto-conical shape for improved grip performance.Of course, other roughened surfaces could be used.

The grip body 170 is constructed of a resilient material, such as a softthermoplastic elastomer (TPE). To provide optimum comfort as well ascontrol benefits, the resilient materials of the grip body 170preferably has a hardness durometer in a range of A11 to A15 Shorehardness. Of course, materials outside this hardness range could also beused. As an example, one preferred elastomeric material for the gripbody 170 is styrene-ethylene/butylene-styrene (SEBS) manufactured by GLSCorporation. Nevertheless, other manufacturers can supply the SEBSmaterial and other materials could be used.

Preferably, the grip body 170 is constructed of a different type ofresilient material than that which the grip cover 160 is constructed.For example, it is preferred that the grip body 170 be constructed of aresilient material having a different hardness as compared to thehardness of the grip cover 160. The material of the grip body 170 ispreferably softer than the material forming the grip cover 160. In thismanner, the handle 110 may be provided with different grip features tocomplement the particular control need. The material of the resilientgrip body 170 and the grip cover 160 are preferably each a thermoplasticelastomer.

Referring now to FIGS. 1, 5 and 6 concurrently, the structuralcooperation of the four components 140, 150, 160, 170 of the toothbrush100 will now be described in detail with respect to a preferredconstruction. In the preferred construction, the elongated handle body150 is constructed of opaque PP, the core structure 140 is constructedof transparent SAN, the grip body 170 is constructed of a TPE having afirst hardness, and the grip cover 160 is constructed of a TPE having asecond hardness that is greater than the first hardness.

The core structure 140 is disposed within and fills the through slot 250of the elongated handle body 150. As a result, the core structure 140 ispartially surrounded by the elongated handle body 150 in acircumferential manner. More specifically, the core structure 140 iswithin the through slot 250 so that the elongated handle body 150overlies (and thus covers) only the front and rear surfaces 143, 144 ofthe core structure 140. The right and left lateral surfaces 141, 142 ofthe core structure 140 protrude from the through slot 250 and remainexposed on the handle 110 so that a user can view into and/or throughthe core structure 140. In essence, the core structure 140 provides awindow into and through the handle 110.

The core structure 140 is located within the through slot 250 so thatthe protuberances 240-243 of the core structure 140 extend into thethrough holes 256 of the elongated handle body 150. As a result, thecontact surfaces 244-247 of the core structure 140 are exposed in thethrough holes 256 of the elongated handle body 150. The extension of theprotuberances 240-243 into the through holes 256 provides a mechanicalconnection between the core structure 140 and the elongated handle body150 that assists in preventing unwanted relative rotation and/orseparation of the core structure 140 from the elongated handle body 150during repeated use. Such a mechanical connection is desirable as theSAN of the core structure 140 and the PP of the elongated handle body150 do not form a chemical bond with each other during the injectionmolding process.

Additionally, the inner arcuate ridges 252 of the elongated handle body150 extend into and nest within the arcuate grooves 248 of the corestructure 140, thereby increasing the mechanical fitting connectionbetween the core structure 140 and the elongated handle body 150.

The grip body 170 is disposed within and fills the aperture 155 of theelongate handle body 150. The convex front and rear surfaces 171, 172 ofthe grip body 170 bulge from the aperture 155 and form a portion of thefront and rear surfaces 111, 112 of the overall handle 110. The gripbody 170 is preferably formed in the aperture 155 via a one or two shotinjection molding technique. The tapered shape of the sidewalls 156 ofthe aperture help retain the grip body 170 within the aperture over thelife cycle of the toothbrush 100. Additionally, a chemical bond may beformed between the TPE of the grip body 170 and the PP of the elongatedhandle body 150 during the injection molding process.

The grip cover 160 is applied to the outer surface of the elongatedhandle body 150 once the core structure 140 is properly located withinthe through slot 250 as discussed above. More specifically, the gripcover 160 is fixed to the elongated handle body 150 so that: (1) thefront leg 161 of the grip cover 160 nests within the portion of thechannel 254 on the front surface 151 of the elongated handle body 150;(2) the curved portion 165 of the grip cover 160 nests within theportion of the channel 254 that wraps around the proximal end 255 of theelongated handle body 150; and (3) the rear leg 162 of the grip cover160 nests within the portion of the channel 254 on the rear surface 152of the elongated handle body 150. As a result, the grip cover 160overlies and conceals the through holes 256 of the elongated handle body150. More specifically, the front leg 261 overlies and conceals thethrough holes 256 on the front surface 151 of the elongated handle body150 while the rear leg 262 overlies and conceals the through holes 256on the rear surface 152 of the elongated handle body 150.

The outer arcuate ridges 257 of the elongated handle body 150 extendinto the openings 166 of the grip cover 160 but remain depressed belowthe rear surface 164 of the rear leg 162 of the grip cover 160 asdiscussed above. The grip cover 160 fills the channel 254, therebywrapping around the proximal end 155 of the elongated handle body 150and surrounding the aperture 155 on both the front and rear surfaces151, 152 of the elongated handle body 150. The grip cover 160 also fillsthe transverse channels/slots between the outer arcuate ridges 257 ofthe elongated handle body 150.

The grip body 160 is fixed to the elongated handle body 150 by achemical bond that is formed between the TPE of the grip cover 160 andthe PP of the elongated handle body 150 during the injection moldingprocess. Finally, while grip cover 160 is shown as a single unitarymember or layer, it could be formed by separate independent parts orsections in certain embodiments.

Referring now to FIGS. 8-10, a method of manufacturing the toothbrush100 according to one embodiment of the present invention will bedescribed.

The first component created in manufacturing the toothbrush 100 is thecore structure 140. To create the core structure 140, a first mold isprovided having a first mold cavity and at least one port/nozzle forinjecting liquefied SAN into the first mold cavity. Preferably a singleport is used to inject the liquefied SAN. The first mold cavity has avolume that is sized and shaped to correspond to the core structure 140.The first mold may be two-part mold, as is known in the art. Once thefirst mold cavity is created/provided, liquefied SAN is injected intothe first mold so as to fill the first mold cavity. The liquefied SAN isallowed to cool to an appropriate temperature so as to form the corestructure 140, as shown in FIG. 8, for further handling.

Once the core structure 140 is created (and allowed to adequately coolfor further handling), the core structure 140 is supported by one ormore clamping members that engage one or more points of contact on thecontact surfaces 244-247 with at least one set of arms.

Once the clamping member is properly supporting the core structure 140through surface contact created between its arms and the contactsurfaces 244-247, the core structure 140 is positioned within a secondmold cavity of a second mold. This positioning can be effectuated byeither moving the core structure 140 into the second mold cavity or bycreating the second mold cavity about the core structure 140 whilesupporting the core structure 140 in a stationary manner, which can beaccomplished by translating and mating multiple pieces of the secondmold into position so that the second mold cavity is formed about thecore structure 140. The second mold cavity has a volume that is sizedand shaped to correspond to the handle assembly 190 (FIG. 9). One ormore ports are present in the second mold for injecting liquefied PPinto the second mold cavity. Preferably a single port is used to injectthe liquefied PP.

Once the core structure 140 is in proper position within the second moldcavity (and the second mold cavity is adequately sealed), the liquefiedPP is injected into the second mold cavity so as to fill the remainingvolume of the second mold cavity that is not occupied by the corestructure 140. The liquefied PP partially surrounds the core structure140, which remains supported by the clamping member (as described above)during the injection and filling of the second mold cavity with theliquefied PP.

The liquefied PP is then allowed to cool to an appropriate temperature,thereby forming the elongated handle body 150 about the core structure140, as shown in FIG. 9. The core structure 140 and elongated handlebody 150 collectively form a handle assembly 190 (illustrated in FIG.9). As a result of the core structure 140 being supported at the contactsurfaces 244-247 by the arms of the clamping member during the formationof the elongated handle body 150, the liquefied PP surrounds the arms ofthe clamping (and does not cover the contact surfaces 244-247). Thus,upon cooling of the liquefied PP (i.e., the formation of the elongatedhandle body 150), the removal of the arms of the clamping member fromthe core structure 140 results in through holes 256 being formed in thefront and rear surfaces 151, 152 of the elongated handle body 150through which the contact surfaces 244-247 are exposed. The SAN materialof the core structure 140 does not chemically bond with the PP of theelongated handle body 150 during the injection molding process.

Once the handle assembly 190 is sufficiently cool for further handling,the handle portion 110 is positioned within a third mold cavity of athird mold. The handle assembly 190 is preferably supported by the head120 during this process. The third mold cavity has a volume that issized and shaped to receive the handle portion 110 of the handleassembly 190 while leaving a remaining volume open that corresponds tothe grip cover 160. One or more ports are present in the third mold forinjecting liquefied TPE into the remaining volume of the third moldcavity. Preferably a single port is used to inject the liquefied TPE ofthe grip cover 160.

Once the handle portion 110 of the handle assembly 190 is in properposition within the third mold cavity, the liquefied TPE is injectedinto the third mold cavity so as to fill the remaining volume of thethird mold cavity that is not occupied by the handle portion 110 of thehandle assembly 190. As a result, the liquefied TPE fills the channel254 of the elongated handle body 150 thereby forming an overmolded gripcover 160 that is fixed to the elongated handle body 150. The TPE of thegrip cover 160 is then allowed to cool. The TPE material of the gripcover 160 chemically bonds with the PP of the elongated handle body 150during this injection molding process.

Either before, after or simultaneously with forming the grip cover 160,the aperture 155 of the elongated handle body 150 is filled with a softTPE to form the grip body 170. This is achieved by injecting theliquefied soft TPE into the aperture 155, which is enclosed by anappropriate mold, via a port that is in fluid communication with theaperture 155. The mold can be a fourth mold or it can be the third mold.In instances where the third mold is used, the third mold would includea fourth mold cavity that is isolated from the third mold cavity. TheTPE material of the grip body 170 chemically bonds with the PP of theelongated handle body 150 during this injection molding process.

The inventive aspects discussed above may be practiced for a manualtoothbrush or a powered toothbrush. In operation, the previouslydescribed features, individually and/or in any combination, improve thecontrol, grip performance, aesthetics and cost point of oral implements.Other constructions of toothbrush are possible. For example, the head120 may be replaceable or interchangeable on the handle 110. The head120 may include various oral surface engaging elements, such asinter-proximal picks, brushes, flossing element, plaque scrapper, tonguecleansers and soft tissue massages. While the various features of thetoothbrush 100 work together to achieve the advantages previouslydescribed, it is recognized that individual features andsub-combinations of these features can be used to obtain some of theaforementioned advantages without the necessity to adopt all of thesefeatures in an oral care implement.

While the invention has been described with respect to specific examplesincluding presently preferred modes of carrying out the invention, thoseskilled in the art will appreciate that there are numerous variationsand permutations of the above described systems and techniques. It is tobe understood that other embodiments may be utilized and structural andfunctional modifications may be made without departing from the scope ofthe present invention. Thus, the spirit and scope of the inventionshould be construed broadly as set forth in the appended claims.

What is claimed is:
 1. A method of forming a handle for an oral careimplement, the method comprising: a) injecting a first hard plastic intoa first mold cavity to form a core structure of the first plastic, thecore structure comprising a distal end extending to a proximal endthereof; b) transferring the core structure from the first mold cavityto a second mold cavity and supporting the core structure within thesecond mold cavity with a gripping member contacting the core structureat two or more points of contact on an outer surface of the corestructure; c) injecting a second hard plastic into the second moldcavity to form an elongated handle body at least partially surroundingthe core structure from the second plastic, thereby forming a handleassembly comprising the elongated handle body and the core structure,the elongated handle body having a through hole formed therein for eachof the two or more points of contact; d) removing the gripping memberfrom the handle assembly and transferring the handle assembly to a thirdmold cavity, the core structure being exposed at each of the points ofcontact via the through holes upon said removing; and e) injecting asoft resilient plastic material into the third mold cavity to form agrip cover over the elongated handle body from the resilient material,thereby forming the handle from the handle assembly and grip cover, thegrip cover overlying the through holes of the elongated handle body tocontact each of the exposed points of contact of the core structure,wherein the elongated handle body covers both of the distal and proximalends of the core structure, and wherein a chemical bond is formedbetween the resilient material and the second plastic during step e). 2.The method of claim 1 wherein the first plastic is a substantiallytransparent hard plastic, the second plastic is an opaque hard plastic,and the resilient material is an opaque TPE.
 3. The method of claim 2wherein the first plastic is SAN and the second plastic is PP.
 4. Themethod of claim 1 wherein the elongated handle body is formed topartially surround the core structure so that opposing lateral surfacesof the core structure remain exposed.
 5. The method of claim 1 wherein achemical bond is not formed between the first plastic and the secondplastic during step c).
 6. The method of claim 1 wherein the corestructure comprises first and second protuberances, wherein the pointsof contact are located on the first and second protuberances, andwherein the first and second protuberances extend into the through holesof the elongated handle body.
 7. The method of claim 1 wherein theelongated handle body has a proximal end, the proximal end of theelongated handle body covered by the grip cover.
 8. The method of claim1 wherein the grip cover covers at least a portion of front and rearsurfaces of the elongated handle body.
 9. The method of claim 1 whereinthe grip cover covers at least a portion of front and rear surfaces ofthe elongated handle body and a proximal end of the elongated handlebody.
 10. The method of claim 1 wherein the core structure furthercomprises a first protuberant structure located at the distal end of thecore structure, the first protuberant structure comprising a first upperprotuberance and a first lower protuberance.
 11. The method of claim 10wherein the first upper protuberance comprises one of the points ofcontact.
 12. The method of claim 11 wherein the first lower protuberancecomprises one of the points of contact.
 13. The method of claim 10wherein at least one of the through holes of the elongated handle bodyis formed on a front surface of the elongated handle body and at leastone of the through holes of the elongated handle body is formed on arear surface of the elongated handle body, the first upper protuberanceextending through at least one of the through holes on the front surfaceof the elongated handle body and the first lower protuberance extendingthrough at least one of the through holes on the rear surface of theelongated handle body.
 14. The method of claim 10 wherein the corestructure further comprises a second protuberant structure located atthe proximal end of the core structure, the second protuberant structurecomprising a second upper protuberance and a second lower protuberance.15. The method of claim 14 wherein the second upper and second lowerprotuberances each comprise one of the points of contact.
 16. The methodof claim 14 wherein at least two of the through holes of the elongatedhandle body are formed on a front surface of the elongated handle bodyand at least two of the through holes of the elongated handle body areformed on a rear surface of the elongated handle body, the first upperprotuberance and the second upper protuberance extending throughrespective ones of the through holes are formed on the front surface ofthe elongated handle body, and the first lower protuberance and thesecond lower protuberance extending through respective ones of thethrough holes are on the rear surface of the elongated handle body. 17.The method of claim 1 wherein the handle has a longitudinal axisextending from a proximal end of the handle to a distal end of thehandle, the longitudinal axis lying on a transverse plane which extendsbetween a front surface of the handle and a rear surface of the handle,and at least two of the two or more points of contact are coincidentwith the transverse plane, one of the two or more points of contactcoincident with the transverse plane being between the front surface andthe longitudinal axis and another one of the two or more points ofcontact coincident with the transverse plane being between the rearsurface and the longitudinal axis.
 18. The method of claim 17 whereintwo of the two or more points of contact coincident with the transverseplane are between the front surface and the longitudinal axis andanother two or more of the two or more points of contact coincident withthe transverse plane are between the rear surface and the longitudinalaxis.
 19. The method of claim 1 wherein one of the points of contact ofthe two or more points of contact is on a first protuberance at thedistal end of the core structure and another point of contact of the twoor more points of contact is on a second protuberance at the proximalend of the core structure, the points of contact on the first and secondprotuberances being on opposite ones of front and rear surfaces of thecore structure.